This invention relates to a static eliminator.
Static electricity is eliminated or removed as a harmful object in the industrial field where a semiconductor is handled or a surface treatment such as coating, plating, or evaporating is conducted. Conventional static electricity eliminating or removing instruments or tools, hereinafter referred to as static eliminator, will be explained below.
(1) Ionizer:
The ionizer ionizes an air and sprays out or issues out ions. The ionizer is attached to the machine to eliminate or remove static electricity from the work, or is held and moved by the operator to remove electricity from the work. In the former case, the work is put on the working table to which the ionizer is attached, and the ionizer is caused to issue ions toward the work and remove electricity from the work. In the latter case, the operator holds the ionizer so as to direct the ions from the ionizer toward the work and remove electricity from the work.
(2) Wrist Strap:
The wrist strap or conductive band is tied on the wrist of the operator to remove electricity from the human body. This is merely to remove electricity from the operator who sits at a working table on which the work is put, and electricity cannot be removed from the walking operator. Actually, the operator sometimes walks around without the wrist strap. Therefore, for the next operation, the operator would forget to tie the wrist strap on his wrist. Furthermore, the wrist straps are connected to the ground at the earth points by the electric wires. However, since the wires are connected to the wrist straps through many junctions, many accidents would be caused.
(3) Anti-static Electricity Clothes:
The operator wears clothes on which less static electricity is generated to prevent the generation of static electricity. The clothes can reduce the generation of static electricity, but cannot remove the generated electricity.
(4) Conductive Shoes:
The shoes which are used during the operation are made to be conductive, The shoes transfer the static electricity generated on the human body to the conductive floor. In this case, the conductive floor is required and the ordinary floor or non-conductive floor is not effective.
(5) Passive Electricity Removing Tool:
(a) Ring type
The ring type of the electricity removing tool is fit on the finger of the operator for use. The tool discharges the electric charges to escape the charges in the air when the charges are accumulated above a static potential, and then lowers the static potential. However, since the discharge of the electricity removing tool stops when the charges lowers below a certain static potential, the removing tool cannot remove a low static potential.
(b) Wrist watch type
The wrist watch type of the electricity removing tool is fit on the wrist of the operator for use. The tool discharges the electric charges to escape the charges in the air when the charges are accumulated above a static potential, and then lowers the static potential. However, since the discharge of the electricity removing tool stops when the charges lowers below a static potential, the removing tool cannot remove a relative low static potential.
Even when one of these electricity removing instruments or tools is used, electricity removement is rather difficult in the following cases. For example, when the operator walks around, the clothes causes the friction therebetween and then the electricity is generated to be accumulated on the human body. If the socks are made of conductive fibers, shoes are conductive, and the floor is conductive, the accumulated static electricity can escape from the human body. However, since in general the operator is not in a such environment, there are problems to be solved. For example, when the operator bearing charges touches the work, the work is electrically attacked and then broken. For another example, the dust on which the charge is accumulated is transferred to the work and then causes damage to the work. As mentioned above, conventionally, a perfect method of removing electricity from the walking operator was not present.
Furthermore, an air tool such as a cutter or buff is used when a big object such as a plastic ship body is machined, e.g. is cut or is ground. Since an air hose which connects an air source to the air tool is usually made of an insulator material where static electricity does not escape, the static electricity generated due to the friction during machining is accumulated on the human body through the air hose. As the static electricity or electric charge is accumulated up to a certain level, the discharge is abruptly caused toward the floor to give a big electric attack to the operator. In such a case, since the operator walks around, there is no perfect method of removing electricity.
A conventional ionizer includes an air-blow gun type of electricity. As shown in FIG. 43, The conventional air-blow gun type of static eliminator 600 is constructed so that an air blow bun is provided with an electric section, that is, a discharge electrode of ionizer. The air-blow gun comprises a cylindrical gun body 602 through which a compressed air is flowed, an air hose 604 through which the compressed air is supplied to the gun body 602, and air nozzle 606 provided at the leading end of the gun body 602.
The air blow gun is provided with a discharge electrode section 608 which comprises a cylindrical insulator 608a provided between the gun body 602 and the air nozzle 606. and a discharge needle 608b disposed on the center of the cylindrical insulator 608a. The discharge needle 608b is applied with a high voltage from a high voltage generator 610 through a high voltage cable 612.
Another conventional air-blow gun type of static eliminator is constructed so that a high voltage generator is disposed integrally with an gun body.
These conventional air-blow gun type of static eliminators are common in that a high voltage discharge electrode section is incorporated in the air-blow gun section or structure. For this reason, conventional air-blow gun type of static eliminator has a disadvantage described below.
(1) The air-blow gun uses a compressed air. The compressed air is carried up to the air-blow gun in which the air is expanded abruptly. Since the air is given adiabatic expansion and cooled, the generation of water droplets in the air-blow gun is inevitable. As shown in FIG. 44 which is a cross-sectional view of the electric section, that is, discharge electrode section of the air-blow gun type of static eliminator, the air-blow gun is always attended with the generation of droplets. The electric is leaked from the discharge needle 608b of high voltage electrode or the high voltage cable 612 via the water droplets. That is, electric leakage is generated. As a result, the operator working while carrying the air-blow gun by hand would be in danger from an electric shock or electrification.
FIG. 45 is a view for a model of an electric circuit showing the status of the electric leakage. In FIG. 45, the high voltage V0 made in the high voltage generating circuit 622 is led to the discharge needle through a current limiting resistor R. Assuming that voltage drop across the current limiting resistor R is VD, the discharge voltage is V1, the discharge current is I1, and the leak current is I2.
V1=V0xe2x88x92VD.
VD=(I1+I2)R
Now, assuming that the high voltage V0 is 5 KV, the current limiting resistor is 100 M ohms, and the discharge current is 1 microampere, and there is no leakage, that is, I2 is 0,
VD=(1*10xe2x88x926)*(100*1066)=100 V.
and then the discharge needle voltage (V0xe2x88x92VD)=5 KVxe2x88x92100 V=4.9 KV.
On the other hand, assuming that there is a leakage and the leakage current is 50 microampere,
VD=(1*10xe2x88x926+50*10xe2x88x926)*(100*106)=5,100 V,
and then the discharge needle voltage=5 KVxe2x88x925.1 KV nearly equals 0 KV.
The voltage at the discharge needle decreases due to the leakage and the discharging is caused to stop.
As mentioned above, when the leakage is generated due to the attachment of the water droplets to the high voltage section, the function of removing electricity is damaged and the electric shock accident would occur.
(2) The discharge needle incorporated in the air-blow gun readily becomes dirty and always must be cleaned. However, since the discharge needle is incorporated inside of the gun, the cleaning is difficult.
(3) The air-blow gun is a mechanical apparatus, and is made strongly enough to be resistant to the high pressure since the compressed air is used. Even if it is handled roughly, it is made strongly enough to be resistant to the water and oil. On the other hand, the static eliminator is a electric apparatus which must be electrically insulated completely to avoid the leakage since it is weak in moisture and the high voltage is used.
As mentioned above, the air-blow gun and the static eliminator themselves are quite different from each other in nature. However, they have been forced to be combined, and as a result there has been an inevitable problem of the leakage.
Another conventional static eliminator has a plus discharge needle and a minus discharge needle. These needles are disposed in parallel so as to issue plus ions and minus ions toward the object to be discharged. For miniaturization of the static eliminator, the distance between the pair of plus and minus discharge needles must be reduced. With the conventional static eliminator, the leading end of the discharge needle projects outwardly from its case, not shown.
With a still another conventional static eliminator, a pair of needles are disposed within the case. The conventional static eliminator prevents the operator from touching the needles inadvertently since the needles are applied with high voltage.
However, as the needles of the static eliminator are disposed adjacent to each other, the plus ions and minus ions generated are caused to be recombined immediately because of the pulling of each other by the coulomb force, and then the ions thus generated disappear. As a result, the electric power is wasteful and the quantity of ions which can be taken out effectively becomes short, and then its efficiency is decreased.
Furthermore, when the discharge needles are covered by the case, the ions which are not issued outside through the discharge apertures are confined in the case and the plus and minus ions are recombined. As a result, in a similar manner as mentioned above, the electric power is wasteful and the quantity of ions which can be taken out effectively becomes short, and then its efficiency is decreased.
Furthermore, conventional static eliminators take no consideration of the dust in the air, there is no static eliminator which has an air cleaning effect.
In the meanwhile, conventionally, as shown in FIG. 42, a main method of measuring static potential comprises positioning a measuring electrode 504 at a certain distance near from the object 500 to be measured, measuring electric field or electric force line from the object 500, and calculating back the static potential of the object 500. In this case, a static electric shelter 502 provided with opening is disposed in front of the measuring electrode 504, and the shelter 502 is mechanically or physically vibrated to measure an electric field. The measured value thus obtained by the measuring electrode 504 is amplified by an amplifier 506 and read by a meter 508. However, this measuring method uses a complicated structure, is weak in the vibration or shock and is expensive.
In view of the foregoing, it is an object of the invention to provide a wear-type of static electricity removing instrument, which can eliminate or remove static electricity accumulated on the operator walking around.
To accomplish the above-mentioned object, there is provided a wear-type of static eliminator which comprises a static eliminator body attachable to the human body, and a discharge section disposed within said remover body to issue ions toward the human body.
It is another object of the invention to provide a static eliminator which can remove static electricity from the human body and simultaneously remove static electricity from the work.
To accomplish the above-mentioned object, there is provided a portable static eliminator which comprises a remover body, said remover body including discharging means of issuing ions in two directions inside, said discharging means having two discharge needles, one disposed to be directed toward the human body and the other disposed to be directed toward a work.
It is a further object of the invention to provide a novel static potential measuring instrument.
It is a still further object of the invention to provide a static eliminator utilizing a priciple of a novel static potential measurement.
It is a still further object of the invention to provide a static eliminator having a static potential measuring function.
To accomplish these objects, there is provided a static potential measuring instrument which comprises a plus discharge needle for use in plus ion discharge, a minus discharge needle for use in minus ion discharge, a current source for generating a current supplied to said plus discharge and minus discharge needles, a plus current ammeter for measuring a current flowing from said current source to said plus discharge needle, a minus current ammeter for measuring a current flowing from said current source to said minus discharge needle, means of calculating the difference between absolute values of currents obtained by said ammeters, the ratio of one absolute value of current obtained by one of said ammeter to the other absolute value of current obtained by the other of said ammeter or both the difference and the ratio, and a measuring terminal connected to said current source.
There is also provided a static eliminator which comprises a plus discharge needle for use in plus ion discharge, a minus discharge needle for use in minus ion discharge, a current source for generating a current supplied to said plus discharge and minus discharge needles, and a connecting terminal connected to said current source.
There is also provided a static potential measuring instrument and static eliminator which comprises a plus discharge needle for use in plus ion discharge, a minus discharge needle for use in minus ion discharge, a current source for generating a current supplied to said plus discharge and minus discharge needles, a plus current ammeter for measuring a current flowing from said current source to said plus discharge needle, a minus current ammeter for measuring a current flowing from said current source to said minus discharge needle, means of calculating the difference between absolute values of currents obtained by said ammeters, the ratio of one absolute value of current obtained by one of said ammeter to the other absolute value of current obtained by the other of said ammeter or both the difference and the ratio, and a measuring terminal connected to said current source.
It is a still further object of the invention to provide an air-blow gun type of static eliminator which can prevent an electric leakage.
To accomplish the object, there is provided an air-blow gun type of static eliminator in which an electric system section having discharge needles for issuing ions and an air-blow gun system section having an air nozzle for ejecting air are configured so that they are independent electrically and machanically.
It is a still further object of the invention to provide a static eliminator which can prevent the rejoining of ions and eliminate useless power consumption.
To accomplish the object, there is provided a static eliminator which comprises a plus discharge needle, a minus discharge needle, and at least one partition wall provided between said discharge needles.